File Coverage

blib/lib/Digest/PSHA.pm

Criterion	Covered	Total	%
statement	18	41	43.9
branch	0	10	0.0
condition	0	3	0.0
subroutine	6	9	66.6
pod	0	2	0.0
total	24	65	36.9

package Digest::PSHA;

# $Id: PSHA.pm,v 1.2 2014-10-23 12:21:56 swaj Exp $

use 5.0008;
use strict;
use warnings;
use Carp;
use Digest::SHA;
use Digest::HMAC qw / hmac /;

require Exporter;

our @ISA = qw(Exporter);
our @EXPORT_OK = qw / p_sha1 p_sha256 /;
our $VERSION = '0.50';

sub p_sha1
{
    my ($secret, $salt, $bytes, $offset) = @_;
    $bytes = 128 unless defined $bytes;
    substr ( _digest ($secret, $salt, $bytes, $offset, \&Digest::SHA::sha1, length(Digest::SHA::sha1(q{}) ) ),
             $offset/8, $bytes/8);
}

sub p_sha256
{
    my ($secret, $salt, $bytes, $offset) = @_;
    $bytes = 256 unless defined $bytes;
    substr ( _digest ($secret, $salt, $bytes, $offset, \&Digest::SHA::sha256, length(Digest::SHA::sha256(q{}) ) ),
             $offset/8, $bytes/8);
}

sub _digest
{
    my ($secret, $salt, $bytes, $offset, $hash_func, $func_hash_len ) = @_;
    my ($buf1, $buf2, $t);
    $offset = 0 unless defined $offset;

    if ($offset % 8 || $bytes % 8 ) {
        carp  "Wrong parameters length [$bytes] and/or offset [$offset], they are in bits!";
        return undef;
    }

    my $bytes_tot = ($offset + $bytes) / 8 ;
    $buf1 = $salt;
    my $buf = q{};
    for ( my $i=0; $i < $bytes_tot ;) {
        $buf2 = $buf1 = hmac($buf1, $secret, $hash_func);
        substr($buf2, $func_hash_len) = $salt;
        $t = hmac($buf2, $secret, $hash_func);
        for (my $x = 0; $x < length($t); $x++) {
            last if ( $i >= $bytes_tot );
            substr($buf, $i++, 1, substr($t, $x, 1) );
        }
    }
    return $buf;
}

1;

__END__